1. Field of the Invention
The present invention relates to an automatic and improved non-chemical treatment system for the conditioning and cleaning of water. It has specific applicability in the cleaning of water for cooling towers without the need for conventional chemicals such as chlorine and the like.
2. Description of the Related Art
Various types of cooling towers are in use. These cooling towers generally use cooling water which may be used in such things as air conditioning systems, manufacturing processes and other operations that require a circulating loop of cool water, which is open to the air. The water used in these cooling towers must be cleaned or the cooling tower can lose efficiency and therefore waste energy. Problems have occurred in prior art systems for the cleaning of the water used in these systems in that they are generally chemical treatments. If the water is not treated, there is mineral build-up (scale), additional growth of this scale, biological growth (biofilm) and the growth of bacteria, algae, fungi and other viruses which might be present in the water. Various types of cooling have been attempted in the past for water used in other types of environments such as water purification systems used during the Apollo space mission or in swimming pools. Specifically, swimming pool water purification systems using ionization for swimming pools has been shown, for example, in Dadisman, U.S. Pat. No. 4,986,906; Dahlgren, U.S. Pat. No. 4,337,136; Eder U.S. Pat. No. 4,492,618; and Hayes, et al., U.S. Pat. No. 4,525,253. These apparatuses and methods suggest the purifying of water for use in, for example, swimming pools or drinking water by using metal ions created by connecting metal electrodes to a current source. However, the teachings found in swimming pools are not optimum for use in cooling towers, especially when the water is used in industrial processes and the additional chemicals such as chlorination or the like which may be added to swimming pool water may cause problems. Additionally, drinking water purification systems do not solve all the problems present in cooling tower cleaning systems.
Specifically, cooling tower water has a problem in that the pH can vary rather quickly as opposed to a swimming pool where the pH will not change rapidly but must be controlled. Accordingly, the prior art systems suffer from several problems. Furthermore, a pure ionic-type of clarification of the systems such as is shown in the Dahlgren, Eder and Hayes systems, have problems in that to control or to lower the amount of erosion and consequent plating of the electrodes, a reversing current is used. Dadisman attempts to solve this problem by using a constant current source being supplied to the electrodes. However, this does not allow for rapid adjustment of the amount of ionization that is provided by the electrodes and, therefore, is less than optimum.
Cooling tower water is continuously exposed to airborne and organic materials. The build up of bacteria, algae, fungi and viruses present hazards to the tower system and/or the health of the humans encountering the water. For example, it is believed that Legionnaires Disease was caused by the bacterium Legionella pneumophila which will thrive in cooling tower environments. High levels of bacteria also leads to possible microbial influenced corrosion which reduces the efficiency of the cooling tower and thereby wastes energy. Sulfate reducing and iron metabolizing bacteria also destroys iron piping. Moreover, a biofilm coating on a heat exchanger will reduce the heat transfer efficiency of the exchanger and is energy wasteful. The scale and biological deposits reduce the ability of refrigerant condensers and industrial process heat exchangers to transfer heat.
Further, the mineral build up which occurs in cooling towers must be addressed. Thermal and biological mechanisms support the build up of scale deposits of minerals such as calcium and magnesium which are commonly dissolved solids in almost any type of municipal water. As the water in the tower evaporates, these dissolved solids concentrate in the recirculating water and increase in concentration. Biofilms also start to form on the walls or other components of the tower. This causes the biofilm to act as an inherent for mineral micro crystals and over time the deposition of organic and inorganic matter increases the scale thickness, thereby exacerbating the problem and reducing the thermal and energy efficiency of the cooling tower. One major concern of cooling towers is the gradual corrosion of various parts of the tower. Much of the corrosion of cooling towers is associated with bacteria that can create conditions favoring microbiological induced corrosion.
Furthermore, the blow down water which is removed from a cooling tower must be disposed of. This blow down water, if sent down a municipal drain or disposed of manually, requires treatment which is energy wasteful and is expensive.
The present invention overcomes shortcomings and deficiencies noted above with respect to various ionic systems or chlorination systems by providing in an ionic system an automatically controlled stepped current to the cathode and anode of the ionic purification system. Additionally, pH is monitored and controlled during the processing and rather than having to alter the ionization direction, CO2 gas is added into the tower water through a bubbling system producing mild carbonic acid. This acid is used to lower the pH level of the water so as to place it back in the level which is optimum for the ionization system. This continuous monitoring of the pH and the amount of CO2 injected provide significant improvements over prior art systems which have attempted to solely use the ionization as the means to control pH or an offline system is used to control the pH of the water. The combination of the CO2 and the ionization provides a synergistic effect which allows for a continuous maintaining of the pH in the optimum range for the water to be purified by the ionic system.
This feature of this invention has an additional significant advantage over prior systems such as is shown by the Dadisman system by although using a non-alternating current uses a stepped or increased DC current on the electrodes. This allows the electrodes to have an almost instantaneous adjustment being provided to them so as to provide the optimum level of purification of the water.